Priming means for centrifugal pumps



Dec. 15, 1953 A @MSE l PRMING MEANS FOR CENTRIFUGU.. PUMPS Filed March14, 195].

,CQ 7 mgm? AT TORNEYS Patented Dec. 15, 1953 UNITED STATES sagra TENT@MCE Alfred L. Grise, Springfield, Mass., assignor to Gilbert & BarkerWest Springfield, Massachusetts Manufacturing Company, Mass., acorporation of Application March 14, 1951, Serial No. 215,446

4 Claims. t

This invention relates to improvements in priming means for centrifugalpumps.

It has been common heretofore to provide as a priming means for acentrifugal pump, a positively-acting pump, such for example as a rotarypump of the type in which a rotor with radially movable vanes is mountedto rotate in, and on an axis eccentrically of a pump chamber. Thepriming pump needs to be large enough 'to speedily scavenge the suctionpipe and impeller chamber. With a priming pump of this character, it isdesirable to avoid needless work by the priming pump and the resultingloss of power and also wear on the parts after the priming operation hasbeen accomplished.. Prior art examples include a clutch, which uncouplesthe priming pump from its driving means, after priming has been eected;an unloading means for the priming pump, operable after priming has beeneffected to open a by-pass, which interconnects the suction and pressuresides of the priming pump; and a variable capacity priming pump withmeans for reducing its pumping rate after the centrifugal pump has beenprimed.

This invention provides an improved arrangement for the purpose and hasfor an object to utilize the priming pump as a fluid coupling betweenthe drive shaft and the impeller of the centrifugal pump, after thelatter has been primed.

More particularly, the invention has for an object the provision in acentrifugal pump of a priming pump having .relatively rotatable elementsone of which is fixed to the driving shaft and the other to the impellerof the centrifugal pump, with means for frictionally holding theimpeller stationary until liquid ils the priming pump under sumcientpressure to substantially prevent relative movement between saidelements.

These objects will best be understood from the following description ofone illustrative example of the invention in the accompanying drawings,in which:

Fig. l is a sectional elevational view of a centrifugal pump embodyingthe invention;

Fig. 2 an elevational View taken from the right of Fig. l and havingparte breiten away in section to show the priming pump;

Fig. 3 is a fragmentary cross sectional view taken on the line il-S ofFig. 1 and showing the outlet port of the priming pump;

Fig. i is a fragmentary sectional plan view taken on the line -il ofFig. 2; and

(Cl. 10B-113) ik! Fig. 5 is a fragmentary cross sectional View taken onthe line 5-5 of Fig. 1.

Referring tothese drawings; the centrifugal pump includes a main casingl (Fig. l) and a cover section 2, suitablysecured together. as by thecap screws 3, and affording between them a chamber l to receive theimpeller 5. The casing is supported by a standard Ci to which it issuitably secured as by cap screws l. The impeller il, as herein shown,is of the closed type and has a circular series of vanos 3 and a centralaxially-directed eye s leading to the space between the varies. Casing lhas in its end wall a central opening i9, in axial alignment with theimpeller and its eye 9, and in this wall and surrounding the inlet l@are a series of tapped holes li, which enable the flanged end of asuction pipe (not shown) to be clamped to the casing.

rThe casing l has formed therein the volute channel l2 (Fig. 2),surrounding the chamber Il and the impeller 5 and terminating in anoutlet iii. The latter has fixed therein a bushing Hl, providing a seatfor a check valve li, which has guide vanos lo slidably engaging theinner peripheral wall of the bushing. A spring El, acting between across bar i3, which is ixed at its ends to the casing l anddiametrically spans the outlet passage l, and the valve it, holds thelatter to its seat until a sufficient pressure is built up in thecentrifugal pump to open the valve.

The pump, as thus far described, of old and well known form and it willserve as an illustrative example of one form of centrifugal pump, inwhich the priming of 'this invention may be embodied. The invention maybe used with any centrifugal pump does not depend on, nor is it limitedto, the particular details of construction disclosed.

rihe impeller 5 Fig. 1), is supported on the inner end of a drive shaftiii with freedom to turn and move axially thereon. This shaft is mountedin ball bearings 2li in a casing il, the inner hanged end of which issuitably fixed, as indicated, to the outer end of a hollow hub 212 oncover 2. The bearings also hold the shaft l against axial movement. Theopening in the inner end of casing 2l is closed by a cover E3 suitablynxed thereto, as indicated, and located within the hollow hub 22. Thiscover 23 has a stuffing box 2li, or other suitable means, for preventingleakage of liquid into the interior of bearing casing 2l and is alsoprovided with a small annular bearing surface 25. The impeller 5 has ahollow cylindrical hub 25 rotatably mounted in a sleeve 21 in the hub 22of cover 2. The outer end of hollow hub 25 is closed (except for certainpassages later to be described) by a cover 2S, suitably xed to the outerend face of the hollow hub, as indicated. This cover 23 has a smallannular bearing surface 29 (Fig. 5) to engage the surface 25 on cover23. A spring 3G (Fig. l), coiled around the inner end of shaft I9, actsbetween a collar 3l on the shaft and the inner end face of the impeller5 to press the bearing surface 29 against the surface 25 for the purposeof frictionally holding the impeller 5 stationary during the operationof the priming pump to be described.

The priming pump is of the positively-acting displacement type and ismounted within the hollow hub 225 of the impeller 5. As shown in Fig. 2,this hub has a cylindrical pump chamber 32, which is eccentricallydisposed in the hub and receives a cylindrical rotor 33, fixed to shafti9, as indicated. Rotor 33 is radially grooved at angularly spacedintervals to slidably receive blades 3f, which are held with their outeredges pressed against the peripheral wall of chamber 32 by means of twoannular rings 35, mounted one in each of two recesses formed in oppositeends of the rotor. In the inner end wall of the pump chamber 32 is anarcuate recess 35, forming the inlet port of the priming pump, and thisrecess is connected by a series of holes 31 with the inlet eye 9 of theimpeller. The outlet port (Fig. 3) consists of an arcuate groove 38 inthe inner face of the cover 28 and this groove is connected by one ormore holes 35 to the space within the hub 22 and between the covers 23and 28. This space is connected by a conduit 45 to the outlet I3 of thecentrifugal pump at a point above the check valve l5.

The holes 39 provide a restricted outlet for the priming pump. Theyprovide in the aggregate sufficient cross sectional area so as Vtofreely pass all the air or gas that the priming pump can pump but notenough area to pass all the liquid that the pump can pump.

In operation, when power is initially applied to shaft I9, the rotor 33will turn but because the spring 3S presses the bearing face 29 againstthe bearing face 25, the impeller 5 will be frictionally held againstrotation as will also the stator of the priming pump, which is the hubof the impeller. The priming pump draws air and/or gases from thesuction pipe and chamber t through the openings 3T in the impeller 5into the inlet port 35 and expels such air and/or gases through theoutlet port 38, holes 39, into the space within hub 22 and between thecovers 23 and 2li and thence through conduit 40 to the outlet i3 abovecheck valve 5. The holes 39 will pass all the air or gases that can bepumped but they restrict the iiow of liquid. Hence, when the centrifugalpump is primed and liquid enters and fills the pump chamber 32, theliquid cannot escape as fast as it is pumped in and pressure builds upwithin this chamber which pressure soon is suiiicient to bind the hub ofthe impeller to the rotor of the priming pump and cause rotation of theimpeller. The priming pump serves like a fluid clutch or coupling todrive the impeller from the rotor of the priming pump after thecentrifugal pump has been fully primed.

rI'hus, the invention provides a fluid drive from the rotor of thepriming pump to the impeller of the centrifugal pump, whereby after thepriming operation has been effected, relative movement between the rotorand stator of the priming pump is avoided, or substantially reduced, toavoid wear on the blades of the priming pump. The arrangement rendersunnecessary the use of a by-pass to unload the priming pump or a clutchto stop the latter after the priming operation has been accomplished, ashas heretofore been deemed necessary in centrifugal pumps of the classdescribed in order to avoid needless work and loss of power or to avoidwear between the engaged parts of the rotor and the stator of thepriming pump.

What is claimed is:

1. The combination with a centrifugal pump, having a casing providedwith a chamber, having an inlet and an outlet and having an impellermounted to rotate in such chamber, of a priming pump of thepositively-acting displacement type comprising a casing elementaffording within it a pump chamber with an inlet connected to and inunrestricted communication with the first-named inlet and chamber and anoutlet, and a piston element mounted in said second chamber for rotationrelatively thereto and operable on such relative rotation to draw influid from the first to the second inlet and iorce it through the secondchamber to the second outlet, one of said elements being fixed to saidimpeller, a drive shaft fixed to the other of said eiements and passingthrough the impeller and free to turn relatively thereto, saidsecond-named outlet provided with a restricted portion of an area suchas to freely pass all the air and gases that the priming pump piston candraw into and force through the second-named chamber but not all theliquid that such pump piston can draw into the second-named chamber, andmeans for fricticnally holding the impeller to its casing to hold theimpeller and one of the priming pump elements against rotation duringthe priming operation, the priming pump chamber when filled with liquidunder pressure acting as a nuid clutch to drive the impeller from thedriven element oi the priming pump.

2. The combination with a centrifugal pump, having a casing providedwith a chamber, having an inlet and outlet and having an impellermounted to rotate in such chamber; of a priming pump of thepositively-acting displacement type comprising a stator fixed to theimpeller and provided with a chamber having an inlet extending throughthe impeller and connected to and communicating with said rst-namedinlet and an outlet having a portion of restricted area, a pistonrotatably mounted in the second-named chamber for drawing fluid fromsaid inlets into and forcing it through the second-named chamber to theoutlet of the latter, a drive shaft fixed to said piston and passingthrough the impeller and free to turn relatively thereto; means forfrictionally holding the impeller to its casing against rotation, saidportion of restricted area freely passing all the air or gases that thepriming pump piston can draw into the second-named chamber but not allthe liquid that the pump piston can draw into the second-named chamber,whereby after the centrifugal pump has been primed the chamber in thestator becomes filled with liquid under pressure and causes the impellerto be driven from the piston.

3. The combination in a centrifugal pump having a casing provided with achamber having a central inlet and a peripheral outlet and an impellerhaving on one side an inlet communicating with the first-named inlet andon the opposite side a hub provided with a cylindrical priming pumpchamber the axis oi which is eccentric to the axis of the impeller, arotor in the the last-named chamber coaxial with the impeller and havingpiston blades engaging the walls of the priming pump chamber, a driveshaft fixed to the rotor and passing through the impeller and free toturn relatively thereto, said priming pump chamber having an inlet portconnected to and communicating through the impeller with both saidinlets and an outlet port, a conduit connecting said outlet port to thefirstnamed outlet and having a restricted portion of an area such as tofreely pass all the air and gases that the priming pump piston bladescan draw into the priming posite side a hub provided with a cylindricaland having piston blades engaging the walls of the priming pump chamber,a drive shaft xed to the rotor and passing through the impeller and freeto turn relatively thereto, a collar xed to the inner end of said shaft,a spring acting pelier against rotation, said priming pump chamberhaving an inlet passage connected to and communicating through theimpeller with both said inlets and an outlet port, a conduit connectingsaid outlet port to the first-named outlet and having a restrictedportion of an area such as to freely pass all the air and gases that thepriming pump piston blades can draw into the priming pump chamber butnot all the liq- ALFRED L. GRIS. References Cited in the iile of thispatent UNITED STATES PATENTS Number Name Date 1,680,906 Neumann Aug. 14,1928 1,394,165 Drysdale Jan. 1o, 1933 2,134,686 De Lancey Nov. 1, 19382,292,896 Morgan Aug. 11, 1942 2,472,802 Bentley June 14, 1949

